1. Field of the Invention
The invention relates to a method for making a lens barrel, more particularly to a method for making a lens barrel having at least one inner cam groove.
2. Description of the Related Art
A conventional zoom lens assembly for a camera usually includes a lens barrel and a plurality of lenses. The lens barrel is formed with a plurality of blind cam grooves in an inner surface thereof. The lenses have guide pins corresponding to and cooperating with the cam grooves of the lens barrel to change relative distances between the lenses so as to obtain a zooming effect. Since the conventional zoom lens assembly has a relatively large size, the lens barrel can be made using a mold together with a wedge mold core having a plurality of flanges on an outer surface thereof for forming the cam grooves. The lens barrel made thereby has a plurality of blind cam grooves in the inner surface thereof.
However, when it is desired to use the zoom lens assembly in a camera of a camera phone, the space provided in the camera phone for mounting the zoom lens assembly is limited. Therefore, the zoom lens assembly is required to be minimized in size. The aforesaid method cannot be used to make the miniaturized zoom lens assembly applicable to camera phones.
Referring to FIGS. 1 and 2, a mold assembly 1 in conjunction with a mold core 2 was proposed heretofore to make a lens barrel 3 suitable for use in a camera phone. The mold assembly 1 is composed of a plurality of mold portions 101 each formed with a plurality of flanges 1011. The mold core 2 has a smooth outer peripheral surface 201. When the mold assembly 1 is assembled together with the mold core 2 in a manner that the flanges 1011 on the mold portions 101 abut against the smooth outer peripheral surface 201 of the mold core 2, a plastic material can be injected into a molding space defined between the mold assembly 1 and the mold core 2 so as to make the lens barrel 3 having a plurality of cam slots 301 corresponding to the flanges 1011 and extending through the lens barrel 3.
Although the aforesaid prior art can be used to make the lens barrel 3 useful in a miniaturized zoom lens for a camera phone, there are the following disadvantages that need to be addressed:
1. Since the cam slots 301 of the lens barrel 3 extend through the lens barrel 3, the zoom lens assembly that incorporates the lens barrel 3 usually encounters a problem of light leaking through the cam slots 301. Therefore, it is required to add an outer barrel (not shown) to solve the light leakage problem, which in turn increases the production costs.
2. Referring to FIG. 3, since the plastic material usually penetrates into the spaces between the flanges 1011 and the smooth outer peripheral surface 201 of the mold core 2 during the molding process, the lens barrel 3 made by the prior art unavoidably has burr edges 302 formed at the cam slots 301. Therefore, further processing is required to remove the burr edges 302, which also increases the production costs.